This invention relates to the control of the output of a jointly owned generating unit as part of a method for controlling the power flow between interconnected power distribution areas which are individually controlled to maintain their tie line interchange at a preset value while maintaining the system frequency at its preset value. It is desired to allocate a part of the generation of the jointly owned unit to each of the joint owners so as to provide them with regulating output from that unit.
The problem relating to jointly owned regulating units has arisen by virtue of the fact that a number of jointly owned generating units have been installed by utilities as a means of benefiting from the capital and operating economics of larger scale units while at the same time avoiding over-commitment in generating capacity. During the initial years of the installation of jointly owned units, those units were wholly base-loaded at their maximum output level. However, recently utilities have installed jointly owned units to such an extent that those units, when combined with the nuclear units, which did not lend themselves to automatic generation control, constituted such a percentage of the system capacity that there remained insufficient regulating capacity. As a result the joint owners found it necessary to control the output of the jointly owned units so that the joint owners had a share of the jointly owned capacity under automatic control even though the units resided in another control area. Thus, the problem arose as to how the individual areas, which are interconnected, could appropriately control a jointly owned unit so that each of the areas received the desired regulating capacity from that jointly owned unit as an allocated share of its output to enable the individual areas to meet their commitment to maintain their tie line schedules along with the usual requirements of maintaining frequency.
Others have suggested various ways of controlling such jointly owned units. However, in those systems which have been suggested to date, the methods of control have been inadequate to take into account all of the problems which arise from the allocation of portions of the output of the jointly owned unit to the various interconnected areas having a share in the joint ownership which will operate properly under all conditions.
It is therefore an object of this invention to provide an improved method for controlling the power flow between interconnected power distribution areas while maintaining the system frequency at its preset value and allocating a part of the generation of any jointly owned unit amongst the joint owners so as to provide them with regulating output from that unit.